FAO/IAEA Agricultural Biotechnology Laboratory, IAEA Laboratories in Seibersdorf, A-2444 Seibersdorf, and Joint FAO/IAEA Division, P.O. Box 100, A-1400 Vienna, Austria.
Appl Environ Microbiol. 1989 Jul;55(7):1711-6. doi: 10.1128/aem.55.7.1711-1716.1989.
The influence of seed and soil inoculation on bradyrhizobial migration, nodulation, and N(2) fixation was examined by using two Bradyrhizobium japonicum strains of contrasting effectiveness in N(2) fixation. Seed-inoculated strains formed fewer nodules on soybeans (mostly restricted to the tap and crown roots within 0 to 5 cm from the stem base) than did bradyrhizobia distributed throughout the soil or inoculated at specific depths. Nodulation was greater below the depths at which bradyrhizobial cells were located rather than above, even though watering was done from below to minimize passive bradyrhizobial migration with percolating water. The most profuse nodulation occurred within approximately 5 cm below the point of placement and was generally negligible below 10 cm. These and other results suggest that bradyrhizobial migration from the initial point of placement was very limited. Nevertheless, the more competitive strain, effective strain THA 7, migrated into soil to a greater extent than the ineffective strain THA 1 did. Nitrogen fixation resulting from the dual-strain inoculations differed depending on the method of inoculation. For example, the amount of N(2) fixed when both strains were slurried together onto the seed was about half that obtained from mixing the effective strain into the soil with the ineffective strain on the seed. The results indicate the importance of rhizobial distribution or movement into soil for nodulation, nodule distribution, strain competitiveness, and N(2) fixation in soil-grown legumes.
通过使用两种固氮效果不同的慢生根瘤菌（Bradyrhizobium japonicum）菌株，研究了种子和土壤接种对慢生根瘤菌迁移、结瘤和固氮的影响。与分布在土壤中的或接种在特定深度的根瘤菌相比，种子接种的菌株在大豆上形成的根瘤较少（主要局限于距茎基部 0 至 5 厘米的根毛和冠根）。即使从下方浇水以最小化随渗漏水被动迁移的根瘤菌，结瘤也更多地发生在根瘤菌细胞所在深度以下，而不是以上。最丰富的结瘤发生在放置点下方约 5 厘米处，通常在 10 厘米以下可以忽略不计。这些和其他结果表明，根瘤菌从初始放置点的迁移非常有限。然而，竞争能力更强的菌株 THA 7 比无效菌株 THA 1 更能迁移到土壤中。来自双菌株接种的固氮因接种方式而异。例如，当两种菌株一起在种子上混合接种时，固定的 N2 量约为将有效菌株与无效菌株混合接种到土壤中时获得的 N2 量的一半。结果表明，根瘤菌在土壤中的分布或运动对于在土壤中生长的豆科植物的结瘤、根瘤分布、菌株竞争力和固氮非常重要。
